The primary purpose of our work has been to improve measurement of flow in renal arteries and veins. Knowledge of renal blood flow is important, since renal artery narrowing or stenosis might be detected, and its significance determined if accurate flow measurement were possible. The detection of renal arterial stenosis is important since such stenosis is treatable, but if untreated may lead to systemic hypertension and/or chronic renal failure. Most of the research performed to date has been on the development and refinement of techniques for cine phase-contrast (PC) measurement of renal blood flow. Techniques were developed at the Lucas Center for the rapid acquisition of blood flow measurement data, so that the acquisition may be performed within a breathholding interval, a requirement for accurate flow measurement. Two such techniques are TRIADS-PC and Spiral-PC. Methods Studies in normal individuals have been performed, with correlation of the noninvasive MRI measurements to the PAH clearance technique. In our study, reported in the past year in Radiology, an excellent correlation between the two techniques (R2 = .97) was found using TRIADS-PC. This was the first time that the capability of an MR technique to measure renal blood flow accurately in humans was confirmed. Results and Discussion The techniques have since been further refined, including development of the Spiral-PC technique, and new variants of the TRIAD S technique which will permit calculation of blood flow during more phases of the individual cardiac cycles. In the past year, the same general techniques of blood flow measurement have been shown capable of measurement of flow to transplanted kidneys, with our results published in the journal Transplantation.. Recent work has focused on the development of improved techniques for imaging renal arteries and other blood vessels deep within the abdomen; promising preliminary results have been obtained.